sync: Process 'control' data separately

sync/test/engine/syncer_command_test.h

Index: sync/test/engine/syncer_command_test.h
diff --git a/sync/test/engine/syncer_command_test.h b/sync/test/engine/syncer_command_test.h
index e519b6b1d78c8ba55791ea6fe4eae3621dbf064a..e34b05730e08abacd853793b3263cd63b79f4a25 100644
--- a/sync/test/engine/syncer_command_test.h
+++ b/sync/test/engine/syncer_command_test.h
@@ -193,6 +193,19 @@ class SyncerCommandTestBase : public testing::Test,
               command.GetGroupsToChangeForTest(*session()));
   }
 
+  void ExpectGroupsToChange(
+      const ModelChangingSyncerCommand& command,
+      ModelSafeGroup group1, ModelSafeGroup group2,
+      ModelSafeGroup group3, ModelSafeGroup group4) {
+    std::set<ModelSafeGroup> expected_groups_to_change;
+    expected_groups_to_change.insert(group1);
+    expected_groups_to_change.insert(group2);
+    expected_groups_to_change.insert(group3);
+    expected_groups_to_change.insert(group4);
+    EXPECT_EQ(expected_groups_to_change,
+              command.GetGroupsToChangeForTest(*session()));
+  }
+
  private:
   MessageLoop message_loop_;
   scoped_ptr<sessions::SyncSessionContext> context_;